Hi Alex,

As far as I know you should take as less user data as possible. It's already controversial whether the IP addresses should be saved or not. Aside from that, how can you ensure the given information is correct?

as less as possible, thats right. Our Users have to mail either their real name and phone number or their full postal adress.
In case of suspicion we check the data using online-phonebooks or just calling them. Ok, you can´t be 100% sure that the given data is real, but normally these informations will do if something goes to law.
In our former forum we sometimes had this problem when an user-pw was given away or was "stolen" - a short call to the user mostly cleared the problem.

cu,
Stefan